1. Field of the Invention
The present invention relates to a points device for toy railway. More particularly, the present invention relates to control of current-flow to rails, accompanying the switching of a points device.
2. Description of Related Art
The layout of a railway on which a model train car is allowed to run comprises a combination of a plurality of railway units such as straight railways, curved railways and points devices. A points device is used to switch traveling direction of a train approaching the points device and various types of points devices have been offered commercially ranging from multipurpose points devices in which a railway is branched to two railways to, for example, complicated structured points devices such as double-slip points and double-crossover points. A user can constitute a variety of layouts by using a points device corresponding to any applications.
For example, Japanese Patent Publication (Laid-open) No. Tokukai-hei-9-84962-A discloses a semi-selection type of points device for a model train car. This points device has a branched track, which curves from a straight to an oblique lateral direction. The straight track includes a pair of rails, one of which (outer rail) is positioned outside of the other comprising one rail connecting a root of the points device with an end of the straight line. The branch track includes a pair of rails, one of which (outer rail) is positioned outside of the other comprising one rail connecting a root of the points device with an end of the branch line. A current always flows in these outer rails irrespective of any switching direction of the points device. On the other hand, the condition of current-flow to an inner rail on a straight track and an inner rail on a branched track varies with the switching direction of the points device. When the switching direction is directed to the straight track side, although a current flows in the inner rail on the straight track, a current does not flow in the inner rail on the branched track side. On the contrary, when the switching direction is directed to the branched track side, although a current flows in the inner rail on the branched track side, a current does not flow in the inner rail on the straight track side. Thus, a system which also switches the current-flow to rails corresponding to the switching direction of a points device is called “a selection system”, particularly, a system where the condition of current-flow to one rail (for example, inner rail) of a pair of rails forming a track is switched whereas the condition of current-flow to the other rail (for example, outer rail) is not switched (a current is always allowed to flow in the rail) is called “a semi-selection system”.
When a semi-selection system of a points device is used in a layout, it is necessary to divide the layout into a plurality of railway blocks by arranging gaps and to control the current-flow to rails in every railway block. The term “a gap” means a clearance or a groove, and it is a cut-out portion of a rail or a railway in order to separate a current flowing in a rail from others. Since the polarities of a series of rails are the same in a simple layout such as an endless layout and the like where railways are laid in an oval shape, it is unnecessary to divide the layout into a plurality of railway blocks. However, since the polarities of a series of rails are reversed along the rails in a pattern where the traveling direction of a train is reversed such as a reverse layout where railways are laid in a P-shape, a short-circuit is caused thereby. In such a pattern, a gap is provided at both ends of reverse blocks to the current-flow thereto independently of the main track block. Since the number of divisions in railway blocks increases as the layout becomes complicated, it has a disadvantage that the current-flow control system of the layout becomes complicated corresponding thereto. In addition to the foregoing, it also has a disadvantage that it reduces operability and convenience since the user must frequently switch current-flow conditions while a train is allowed to run.